Publications
Filter Total Items: 3083
Aeromagnetic map of the Clear Lake region on parts of the Santa Rosa and Ukih 1° by 2° quadrangles, California Aeromagnetic map of the Clear Lake region on parts of the Santa Rosa and Ukih 1° by 2° quadrangles, California
No abstract available.
Authors
Water Resources Division U.S. Geological Survey
The initial cooling of pahoehoe flow lobes The initial cooling of pahoehoe flow lobes
In this paper we describe a new thermal model for the initial cooling of pahoehoe lava flows. The accurate modeling of this initial cooling is important for understanding the formation of the distinctive surface textures on pahoehoe lava flows as well as being the first step in modeling such key pahoehoe emplacement processes as lava flow inflation and lava tube formation. This model is
Authors
L. Keszthelyi, R. Denlinger
Channel adjustment of an unstable coarse-grained stream: Opposing trends of boundary and critical shear stress, and the applicability of extremal hypotheses Channel adjustment of an unstable coarse-grained stream: Opposing trends of boundary and critical shear stress, and the applicability of extremal hypotheses
Channel adjustments in the North Fork Toutle River and the Toutle River main stem were initiated by deposition of a 2.5km3 debris avalanche and associated lahars that accompanied the catastrophic eruption of Mount St. Helens, Washington on 18 May 1980. Channel widening was the dominant process. In combination, adjustments caused average boundary shear stress to decrease non-linearly with...
Authors
Andrew Simon, Colin R. Thorne
A new model for the emplacement of Columbia River basalts as large, inflated pahoehoe lava flow fields A new model for the emplacement of Columbia River basalts as large, inflated pahoehoe lava flow fields
Extensive flows of the Columbia River Basalt (CRB) Group in Washington, Oregon, and Idaho are dominantly inflated compound pahoehoe sheet lavas. Early studies recognized that CRB lavas are compound pahoehoe flows, with textures suggesting low flow velocities, but it was thought that the great thickness and extent of the major flows required very rapid emplacement as turbulent floods of...
Authors
S. Self, Th. Thordarson, L. Keszthelyi, G.P.L. Walker, K. Hon, M.T. Murphy, P. Long, S. Finnemore
Growth of the Tongariro volcanic complex: New evidence from K-Ar age determinations Growth of the Tongariro volcanic complex: New evidence from K-Ar age determinations
New K-Ar age determinations indicate that the exposed portion of the Tongariro volcanic complex has grown steadily since at least 275 ka, with intervals of vigorous cone growth at 210-200.130-70. and 25 ka to the present day.
Authors
B.J. Hobden, Bruce F. Houghton, M. A. Lanphere, I.A. Nairn
Volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory 1995 Volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory 1995
The Alaska Volcano Observatory (AVO) responded to eruptive activity or suspected volcanic activity (SVA) at 6 volcanic centers in 1995: Mount Martin (Katmai Group), Mount Veniaminof, Shishaldin, Makushin, Kliuchef/Korovin, and Kanaga. In addition to responding to eruptive activity at Alaska volcanoes, AVO also disseminated information for the Kamchatkan Volcanic Eruption Response Team...
Authors
Robert G. McGimsey, Christina A. Neal
Provisional geologic map of Augustine Volcano, Alaska Provisional geologic map of Augustine Volcano, Alaska
No abstract available.
Authors
R. B. Waitt, J. E. Beget, Juergen Kienle
The Loma Prieta, California, Earthquake of October 17, 1989: Main shock characteristics The Loma Prieta, California, Earthquake of October 17, 1989: Main shock characteristics
The October 17, 1989, Loma Prieta, Calif., earthquake (0004:15.2 G.m.t. October 18; lat 37.036º N., long 121.883º W.; 19-km depth) had a local magnitude (ML) of about 6.7, a surface-wave magnitude (MS) of 7.1, a seismic moment of 2.2x1019 N-m to 3.5x1019 N-m, a source duration of 6 to 15 s, and an average stress drop of at least 50 bars. Slip occurred on a dipping fault surface about 35...
Authors
Paul A. Spudich, Gregory C. Beroza, George Choy, John Boatwright, Stephen H. Hartzell, Gordon L. Stewart, Carlos Mendoza, Stephen Horton, John G. Anderson, Andres J. Mendez, Hiroo Kanamori, Kenji Satake, Michael Lisowski, Mark Hunter Murray, Jerry L. Svarc, Grant Marshall, Ross S. Stein, Karen McNally, Gerald W. Simila, Judy G. Brown, J.L. Nabelek, Ze’ev Reches, Mark D. Zoback, Jamison Steidl, Ralph J. Archuleta, Aaron A. Velasco, Thorne Lay, Jiajun Zhang, David J. Wald, Donald V. Helmberger, Thomas H. Heaton, Chesley R. Williams, Paul Segall, Francis T. Wu, Mingdong Wu, J.W. Rudnicki
A catastrophic flood caused by drainage of a caldera lake at Aniakchak Volcano, Alaska, and implications for volcanic hazards assessment A catastrophic flood caused by drainage of a caldera lake at Aniakchak Volcano, Alaska, and implications for volcanic hazards assessment
Aniakchak caldera, located on the Alaska Peninsula of southwest Alaska, formerly contained a large lake (estimated volume 3.7 × 109 m3) that rapidly drained as a result of failure of the caldera rim sometime after ca. 3400 yr B.P. The peak discharge of the resulting flood was estimated using three methods: (1) flow-competence equations, (2) step-backwater modeling, and (3) a dam-break...
Authors
C. F. Waythomas, J. S. Walder, R. G. McGimsey, C.A. Neal
Three-dimensional P and S wave velocity structure of Redoubt Volcano, Alaska Three-dimensional P and S wave velocity structure of Redoubt Volcano, Alaska
The three‐dimensional P and S wave structure of Redoubt Volcano, Alaska, and the underlying crust to depths of 7–8 km is determined from 6219 P wave and 4008 S wave first‐arrival times recorded by a 30‐station seismograph network deployed on and around the volcano. First‐arrival times are calculated using a finite‐difference technique, which allows for flexible parameterization of the...
Authors
H.M. Benz, B. A. Chouet, P.B. Dawson, J.C. Lahr, R.A. Page, J.A. Hole
Outburst floods from glacier-dammed lakes: The effect of mode of lake drainage on flood magnitude Outburst floods from glacier-dammed lakes: The effect of mode of lake drainage on flood magnitude
Published accounts of outburst floods from glacier‐dammed lakes show that a significant number of such floods are associated not with drainage through a tunnel incised into the basal ice—the process generally assumed—but rather with ice‐marginal drainage, mechanical failure of part of the ice dam, or both. Non‐tunnel floods are strongly correlated with formation of an ice dam by a...
Authors
Joseph S. Walder, John E. Costa
Waters associated with an active basaltic volcano, Kilauea, Hawaii: Variation in solute sources, 1973-1991 Waters associated with an active basaltic volcano, Kilauea, Hawaii: Variation in solute sources, 1973-1991
Chemical and isotopic analyses of samples collected from a December 1962-m-deep research borehole at the summit of Kilauea Volcano provide unique time-series data for composition of waters in the uppermost part of its hydrothermal system. These waters have a distinctive geochemical signature: a very low proportion of chloride relative to other anions compared with other Hawaiian waters...
Authors
R.I. Tilling, B.F. Jones